Statically fixed isolation system



1966 WALLERSTEIN, JR 3,288,419

STATICALLY FIXED ISOLATION SYSTEM 5 Sheets-Sheet 1 Original Filed April29, 1963 O/ I w 7w? 7 5ll EH 0 w 25; I 4 T .INVENTOR. $7. Mam/Wk. )7

WW m M FIG. 4

Nov. 29, 1966 WALLERSTEIN, JR 3,

STATICALLY FIXED ISOLATION SYSTEM Original Filed April 29, 1963 5Sheets-Sheet 2 6 INVENTOR. 'El Jim W M BY Nov. 29, 1966 L. WALLERSTEIN,JR 3,283,419

STATICALLY FIXED ISOLATION SYSTEM 5 Sheets-Sheet 5 Original Filed April29, 1963 4 FIGS United States Patent 3,288,419 STATICALLY FIXEDISOLATION SYSTEM Leon Wallerstein, .lr., Erie, Pa, assignor to LordCorporation, Erie, Pa., a corporation of Pennsylvania Continuation ofapplication Ser. No. 276,365, Apr. 29, 1963. This application Jan. 14,1966, Ser. No. 528,690 14 Claims. (Cl. 248-358) This application is acontinuation of application Serial No. 276,365, filed April 29, 1963.

This invention is a vibration isolation system which in a preferredfor-m maintains the isolated equipment in a fixed static relation to itssupporting structure, even though the latter may experience a range ofsustained accetlerations. One advantage is the reduction of clearancerequirements between the equipment and its supporting structure. Anotheradvantage is the ability to maintain translational alignment between theequipment and its supporting structure. Another advantage is vibrationisolation. The term fixed static relation should not be confused withthe dynamic oscillation of the equipment incident to vibrationisolation.

In the drawing, FIG. 1 is a diagrammatic view, FIG. 2 is an elevation ofa vibration isolated inertial platform, FIG. 3 is an end view of theinertial platform, FIG. 4 is a top plan view of the intertial platform,FIG. 5 is a diagrammatic elevation of a modification eliminatingrotational motion of one of the supported masses, FIG. 6 is an elevationof the modification, FIG. 7 is an elevation of another modification, andFIGS. 8 and 9 are a diagrammatic view of hydraulic systems.

In the drawing, 1 indicates the supported mass or isolated equipment(111,), 2 a counterweight (m which may be a useful piece of equipmentassociated with the supported mass 1, and 3 the base or supportingstructure. The mass 1 is supported on one end of a lever 5 pivoted at 6on the base by a spring 4 having spring constant k, and connected to thelever a distance a from the pivot 6. The mass 2 is carried by theopposite end of the lever 4 and a spring 7 having a spring constant kand arranged between the lever 5 and the base and at a distance 11 fromthe pivot 6. A damper 8 may be arranged between the lever 5 and the mass1 and a damper 9 between the lever 5 and 'the base 3. The function ofthe dampers is to limit the excursion at resonance.

As the base is accelerated, the mass 1 is subject to compensatingeffects which maintain the height h above the base constant. Forexample, sustained acceleration of the base 3 upward causes compressionof spring 4 and tends to reduce the height it between the mass 1 and thebase. At the same time, clockwise rotation of the lever 5 occurrs,tending to decrease h. The effects compensate, keeping the height h ofmass 1 above the base constant, it the following relation is satisfied:

where the terms are indicated on FIG. 1. Three parameters are involved,these being the mass ratio (m /m the spring stiffness ratio (k k and thelever ratio (a/b). Fixing any two of these parameters determines thethird, and there are generally two possible values of a/ b for anycombination of 121 /111 and [Cg/k1. Curves have been calculated forratios of a/b from .1 to 2, for ratios of m /m ranging from .25 to 2 andfor spring constants k /k ranging from .01 to 1. There is no theoreticalreason why this range of values cannot be extended.

In FIG. 2, there is shown a mounting system for an inertial platform 10carried in a frame 11 having pro- 3,288,419 Patented Nov. 29, 1966 "icejectin-g arms 12 associated with resilient mountings 13 whichresiliently support the platform on the left hand end of a lever 16pivoted at 17 on a base 18. A counterweight 19 is fixed to the righthand end of the lever 16 and resiliently supported on the base 18 bymounting 20 on bracket 45. This structure permits the inertial platformto be resiliently mounted on the base and yet to maintain asubstantially constant static height relation relative to the base undersustained accelerations. These accelerations which normally stress themountings 13 and thereby cause variations in the height of the inertialplatform about the base are compensated by pivotal movement of the lever16. Since the compensation is obtained by rocking of the lever whichsupports the equipment, there is tilting of i he isolated equipment eventhough the static height above the base remains the same.

FIGS. 5 and 6 show a structure which maintains the isolated equipmentlevel as well as at fixed height above the base. In this construction,the equipment 21 is supported by a spring 22 on a cradle or link 23having its upper end pivoted at 24 to the left hand end of the lever 25and its lower end pivoted at 26 to a link 27 parallel to the lever 25and pivoted at 28 on a bracket 29 fixed to the base 30'. The lever 25 ispivoted at 31 on the bracket 29 forming with the bracket 29 and theassociated links 23, 27 a parallelogram linkage which prvents tilting ofthe equipment relative to the base. In other respects, the operation isthe same as the previously described construction. The counterweight 32which is supported on the base by spring 33 has a compensating actionwhich maintains the equipment 21 at a fixed height above the base 30.The parallelogram linkage prevents rocking or rotational movement of theequipment 21 about the pivot 24.

FIG. 7 shows another system for maintaining equipment at a fixed staticheight above the base and at the same time preventing rotation of theequipment relative to the base. In this system there are twocounterweights 34, 35. The counterweight 34 is fixed to the left handend of a lever 37 supported by a spring 38 between it and base 36. Thelever 37 is pivoted at 39 on the base and the right hand end of thelever supports the right hand end of the equipment 40 by a spring 41.The counterweight 35 is mounted on the right hand end of a lever 42pivoted at 39 on the base and supported by a spring 43 between it andthe base. The levers 37 and 42 may have separate pivots. The left handend of the lever 42 supports the left hand end of the equipment 40 bymeans of a spring 44. From one aspect, each lever (37 or 42) and theassociated counterweight (34 or 35) and spring (38 or 43) maintains itsshare of the equipment 40 at a fixed height above the base.

The systems provide vibration isolation for the equipment 1, 1.0, 21, 40and at the same time maintain the equipment at a fixed static heightabove the base. The counterweights 2, 32, 34, 35, which also may includeequipment, are also provided with vibration isolation but are notmaintained at a fixed static height above the base. The vibrationisolation is provided by dynamic oscillation of the equipment relativeto the base.

In FIGS. 8 and 9 a hydraulic connection is substituted for the lever.Referring just to FIG. 8, the mass 46 (m is supported by a spring 47 (kon a piston 48 of area a slidable in a cylinder 49 fixed to the base 50.The counterweight 51 (m is a part of a piston 52 of area 11 slidable ina cylinder 53 also fixed to the base. A spring 54 (k is arranged betweena part 55 of the base 50 and the counterweight. The cylinders areconnected by a liquid filled line 56 so that whenever the counterweight51 moves down, the piston 48 moves up and vice versa, the ratio of themovement being inversely proportional to the areas of the pistons 48,52. The mas:

46 (m will remain a fixed height above the base if the followingequation is satisfied:

m 2 b k.

which is identical with the expression for the mechanical system, exceptthat the piston area ratio a /a replaces the lever ratio a/ b.

The hydraulic lever has the following advantages:

(1) It can be made very compact since the large and small pistons can beplaced next to each other, or in any convenient location, beingconnected by a 'tube.

(2) As a further size reduction, the two piston-cylinder arrangementscould 'be made concentric (see FIG. 9).

(3) The fluid connection between cylinders could provide damping.

(4) Sliding pistons are not necessary. Diaphragms can be used.

In FIG. 9, the mass 56a (m is supported by spring 57 (k on piston 58 ofarea a The counterweight 59 (m is an annular piston of area 61 (k onbase 63 having cylinders 64, 65 for the pistons. The operation is thesame as FIG. 8. The liquid fill flows through way 66 to transmitmovement from one piston to the other.

What is claimed as new is:

1. A mounting system comprising a base, a mass m a part movable relativeto the base, a resilient mounting k in load carrying relation betweensaid part and the mass 111 a counterweight m a resilient mounting kweight m on said resilient mounting k 2. A mounting system comprising abase, a lever having a pivot on the base intermediate its ends, a firstmass m a 1 m m k b 2 m m k 5. A mounting system comprising a base, amass m I. part movable relative to the base, a resilient mountng k inload carrying relation between said part and the responsive todeflection of iass m on the resilient mounting k for displacing the 1885m in opposition to said deflection.

6. The system of claim 5 in which the means comprises first class leverpivoted to the base intermediate its nds and having one end connected tothe counterweight ad the opposite end connected to said part.

7. The system of claiin 5 having damping means connected between saidpart and the mass m 8. The system of claim 5 having damping meansconnected between said part and said base.

9. A mounting system comprising a base, a mass "2 a piston of area :1 aresilient mounting k in load carrying relation between said piston andthe mass m a counterweight m including a piston of area a a resilientmounting k in load carrying relation between said base and thecounterweight m a hydraulic line with the piston of area al at one endof the line and the piston of area a at the other end of the line fordisplacing said piston of area a in opposition to the deflection of saidresilient mounting k 10. A mounting system comprising a base, a mass 111a plurality of parts movable relative to the base, a plurality ofresilient mountings k respectively in load carrying relation between adiiferent one of said parts and a different portion of the mass m aplurality of counterweights m said parts and said counterweights beingasplurality of resilient mountings k respectively associated with eachcounterweight and in load carrying relation between the associatedcounterweight and said base, and a force transmitting connection betweeneach part and its associated counterweight for moving each part inopposition to the deflection of each counterweight on its associatedresilient mounting k 11. A mounting system comprising a base, a mass m apair of parts movable relative to the base, a pair of resilientmountings k one associated with each part and connected respectively 111load carrying relation between the associated part and a differentportion of the mass, a pair of counterweights, one associated with eachpart, a pair of resilient mountings k one associated with eachcounterweight and connected in load carrying relation respectivelybetween the base and the associated counterweight, a pair of first classlevers, one associated with each part and its associated being incrossed relation to each other and each pivoted which the parts havesubstantially the relation of the following equation:

. said deflection.

14. The mounting system of claim 13 in which the means in load carryingrelation between said part and the mass m supports the mass m formovement relative to said part.

References Cited by the Examiner CLAUDE A. LE ROY, Primary Examiner. R.P. SEITTER, Examiner.

13. A MOUNTING SYSTEM COMPRISING A BASE, A MASS M1, A PART MOVABLERELATIVE TO THE BASE, MEANS IN LOAD CARRYING RELATION BETWEEN SAID PARTAND THE MASS M1, A COUNTERWEIGHT M2, A RESILIENT MOUNTING K2 IN LOADCARRYING RELATION BETWEEN SAID BASE AND THE COUNTERWEIGHT M2 AND MEANSRESPONSIVE TO DEFLECTION OF MASS M2 ON THE RESILIENT MOUNTING K2 FORDISPLACING THE MASS M1 IN OPPOSITION TO SAID DEFLECTION.